A community-based study of acute respiratory tract infections in children in Uruguay

Incidence of acute respiratory infections in preschool children in an outpatient setting before and during Covid-19 pandemic in Lombardy Region, Italy

Introduction

The incidence of acute respiratory tract infections (ARTIs) in children is difficult to estimate because they are typically treated in outpatient settings and the majority of epidemiological data originate from hospital settings and refer to the most severe illnesses. Therefore, the incidence of ARTIs in a real-world setting remains largely unexplored. Therefore, this study aims to estimate the incidence of ARTIs, upper respiratory tract infections (URTIs), and lower respiratory tract infections (LRTIs) in children aged 0–5 years in an outpatient setting.

Methods

This prospective cohort study was conducted in Lombardy, Italy, from October 1st, 2019, to March 31st, 2021, before and during the COVID-19 pandemic that began in March 2020. Caucasian healthy children aged 0–5 years were recruited from 69 Family Pediatricians (FP) and followed-up in an outpatient setting. Data were collected whenever a child was referred to FP and ARTI was diagnosed (Covid-19 related ARTI were excluded). The primary outcome was an estimate of the incidence of ARTIs. The incidence of ARTIs in different age groups and the effect of the COVID-19 pandemic on the incidence of ARTIs were secondary outcomes.

Results

We enrolled 484 children, 249 male (51.8%), mean age of 2.39 ± 1.68 years. The mean estimated incidence of ARTIs was 12.1/100 children × 30 days (95% CIs: 9.5–12.9), with the highest value observed in infants aged 1–12 months (24.9/100 children × 30 days; 95% CIs: 17.6–28.9). The mean estimated incidence of URTIs was higher than that of LRTIs (8.3 – CIs: 7.6–8.9 vs 3.8/100 children × 30 days – CIs: 6.4–4.3, respectively). The comparison of ARTIs, which occurred in the pre-pandemic winter, to those measured during the COVID-19 pandemic, revealed an impressive 82.1% drop in the incidence rate (CIs: 77.8–85.7).

Conclusions

This study showed that infants aged 1–12 months are more likely to develop ARTIs than older children and that COVID-19 pandemic has dramatically altered the epidemiology of ARTIs in children aged 0–5 years.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13052-022-01221-w.

High rates of pneumonia in children under two years of age in a South East Asian refugee population

BACKGROUND

There are an estimated 150 million episodes of childhood pneumonia per year, with 11-20 million hospital admissions and 1.575 million deaths. Refugee children are particularly vulnerable, with poorly defined pneumonia epidemiology.

METHODS

We followed a birth cohort of 955 refugee infants, born over a one-year period, until two years of age. Clinical and radiographic pneumonia were diagnosed according to WHO criteria. Detailed characteristics were collected to determine risk factors for clinical, radiological and multiple episodes of pneumonia. Investigations were taken during a pneumonia episode to help determine or to infer an aetiological diagnosis.

FINDINGS

The incidence of clinical pneumonia was 0.73 (95% CI 0.70-0.75) episodes per child year (/CY) and of radiological primary endpoint pneumonia (PEP) was 0.22/CY (95% CI 0.20-0.24). The incidence of pneumonia without severe signs was 0.50/CY (95% CI 0.48-0.53), severe pneumonia 0.15/CY (95% CI 0.13-0.17) and very severe pneumonia 0.06/CY (0.05-0.07). Virus was detected, from a nasopharyngeal aspirate, in 61.3% of episodes. A reduced volume of living space per person (IRR 0.99, 95% CI 0.99-1.0, p = 0.003) and young maternal age (IRR 1.59, 95% CI 1.12-2.27, p = 0.01) were risk factors for developing pneumonia. The risk of a child having >1 episode of pneumonia was increased by having a shorter distance to the next house (IRR 0.86, 95% CI 0.74-1.00, p = 0.04). Infants were at risk of having an episode of PEP if there was a shorter distance from stove to bed (IRR 0.89, 95% CI 0.80-0.99, p = 0.03). Raised CRP and neutrophil values were associated with PEP.

CONCLUSIONS

There was a high incidence of pneumonia in young children in this SE Asian refugee population. Viral infections were important, however CXR and non-specific marker findings suggested that bacteria may be involved in up to a third of cases.

Epidemiology and etiology of childhood pneumonia

Childhood pneumonia is the leading single cause of mortality in children aged less than 5 years. The incidence in this age group is estimated to be 0.29 episodes per child-year in developing and 0.05 episodes per child-year in developed countries. This translates into about 156 million new episodes each year worldwide, of which 151 million episodes are in the developing world. Most cases occur in India (43 million), China (21 million) and Pakistan (10 million), with additional high numbers in Bangladesh, Indonesia and Nigeria (6 million each). Of all community cases, 7-13% are severe enough to be life-threatening and require hospitalization. Substantial evidence revealed that the leading risk factors contributing to pneumonia incidence are lack of exclusive breastfeeding, undernutrition, indoor air pollution, low birth weight, crowding and lack of measles immunization. Pneumonia is responsible for about 19% of all deaths in children aged less than 5 years, of which more than 70% take place in sub-Saharan Africa and south-east Asia. Although based on limited available evidence, recent studies have identified Streptococcus pneumoniae, Haemophilus influenzae and respiratory syncytial virus as the main pathogens associated with childhood pneumonia.

Acute respiratory symptoms and general illness during the first year of life: a population-based birth cohort study

Respiratory symptoms are common in infancy. Most illnesses occurring among children are dealt with by parents and do not require medical attention. Nevertheless, few studies have prospectively and on a community-basis assessed the amount of respiratory symptoms and general illness in normal infants. In this population-based birth cohort study, 228 healthy infants from Copenhagen, Denmark were followed from birth to 1 year of age during 2004-2006. Symptoms were registered using daily diaries and monthly home visits. Interviews were performed at inclusion and every second month. Risk factor analysis was carried out by multiple logistic regression analysis. On average, children had general symptoms for 3.5 months during their first year of life, nasal discharge being most frequent followed by cough. Frequency of all symptoms increased steeply after 6 months of age. Each child had on average 6.3 episodes (median: 5.1, inter-quartile range (IQR): 3.3-7.8) of acute respiratory tract illness (ARTI) (nasal discharge and > or = 1 of the following symptoms: cough, fever, wheezing, tachypnea, malaise, or lost appetite) and 5.6 episodes (median: 4.3, IQR: 2.1-7.3) of simple rhinitis per 365 days at risk. Determinants for respiratory symptoms were increasing age, winter season, household size, size of residence, day-care attendance, and having siblings aged 1-3 years attending a day nursery. In conclusion, the present study provides detailed data on the occurrence of disease symptoms during the first year of life in a general population cohort and emphasizes the impact of increasing age, seasonality, and living conditions on the occurrence of ARTI.

Burden of acute respiratory infections in a family cohort in Iran

Acute respiratory infections (ARIs) are the most important infectious cause of death, but there is less information of their burden in the community. This study describes the burden of ARI in a cohort of 50 Iranian families visited weekly over 2 months. Eighty-one out of 113 (72%) children and 29/103 (28%) adults had a total of 124 episodes of ARI. Seventy-five per cent of the episodes occurring in children were primary/co-primary compared to 40% of those in adults (P<0.01). Children were more likely to be the first symptomatic cases and infections were frequently transmitted within the family. Frequencies were lowest among adults, low among infants aged <6 months and highest among children aged <5 years (P<0.01). Winter episodes occurred more frequently in January (P<0.01). The high frequency and apparent transmissibility of ARI in this cohort highlights its enormous burden in the community.

Prospectively assessed incidence, severity, and determinants of respiratory symptoms in the first year of life

Respiratory symptoms are common in infancy. Nevertheless, few prospective birth cohort studies have studied the epidemiology of respiratory symptoms in normal infants. The aim of this study was to prospectively obtain reliable data on incidence, severity, and determinants of common respiratory symptoms (including cough and wheeze) in normal infants and to determine factors associated with these symptoms. In a prospective population-based birth cohort, we assessed respiratory symptoms during the first year of life by weekly phone calls to the mothers. Poisson regression was used to examine the association between symptoms and various risk factors. In the first year of life, respiratory symptoms occurred in 181/195 infants (93%), more severe symptoms in 89 (46%). The average infant had respiratory symptoms for 4 weeks and 90% had symptoms for less than 12 weeks (range 0 to 23). Male sex, higher birth weight, maternal asthma, having older siblings and nursery care were associated with more, maternal hay fever with fewer respiratory symptoms. The association with prenatal maternal smoking decreased with time since birth. This study provides reliable data on the frequency of cough and wheeze during the first year of life in healthy infants; this may help in the interpretation of published hospital and community-based studies. The apparently reduced risk in children of mothers with hayfever but no asthma, and the decreasing effect of prenatal smoke exposure over time illustrate the complexity of respiratory pathology in the first year of life.

Nutritional rickets around the world: causes and future directions

INTRODUCTION

Nutritional rickets has been described from at least 59 countries in the last 20 years. Its spectrum of causes differs in different regions of the world.

METHODS

We conducted a systematic review of articles on nutritional rickets from various geographical regions published in the last 20 years. We extracted information about the prevalence and causes of rickets.

RESULTS

Calcium deficiency is the major cause of rickets in Africa and some parts of tropical Asia, but is being recognised increasingly in other parts of the world. A resurgence of vitamin D deficiency has been observed in North America and Europe. Vitamin D-deficiency rickets usually presents in the 1st 18 months of life, whereas calcium deficiency typically presents after weaning and often after the 2nd year. Few studies of rickets in developing countries report values of 25(OH)D to permit distinguishing vitamin D from calcium deficiency.

CONCLUSIONS

Rickets exists along a spectrum ranging from isolated vitamin D deficiency to isolated calcium deficiency. Along the spectrum, it is likely that relative deficiencies of calcium and vitamin D interact with genetic and/or environmental factors to stimulate the development of rickets. Vitamin D supplementation alone might not prevent or treat rickets in populations with limited calcium intake.

A potential role for vitamin D on HIV infection?

Despite advances in the knowledge of vitamin D's potent immunomodulatory activity, its role on HIV disease progression is unknown. Decreased concentrations of 1alpha,25-hydroxyvitamin D3, or 1,25(OH)2D, the active form of vitamin D, have been reported among HIV-infected people and attributed to defects in renal hydroxylation and increased utilization. A few studies also described low levels of 25-hydroxyvitamin D3, 25(OH)D, the vitamin obtained from solar synthesis and diet. An inverse association between 1,25(OH)2D concentrations and mortality has been reported from a small cohort of HIV-infected adults, and some cross-sectional studies have indicated positive correlations between 1,25(OH)2D and CD4+ cell counts. Additional observational studies are needed to confirm the associations between vitamin D status and HIV disease progression. These investigations would provide useful insights on the potential role of vitamin D supplementation to HIV-infected persons and the planning of intervention trials.

Molecular epidemiology of human respiratory syncytial virus in Uruguay: 1985-2001--a review

The variability of the G glycoprotein from human respiratory syncytial viruses (HRSV) (groups A and B) isolated during 17 consecutive epidemics in Montevideo, Uruguay have been analyzed. Several annual epidemics were studied, where strains from groups A and B circulated together throughout the epidemics with predominance of one of them. Usually, group A predominates, but in some epidemics group B is more frequently detected. To analyse the antigenic diversity of the strains, extracts of cells infected with different viruses of group A were tested with a panel of anti-G monoclonal antibodies (MAbs). The genetic variability of both groups was analyzed by sequencing the C-terminal third of the G protein gene. The sequences obtained together with previously published sequences were used to perform phylogenetic analyses. The data from Uruguayan isolates, together with those from the rest of the world provide information regarding worldwide strain circulation. Phylogenetic analyses of HRSV from groups A and B show a model of evolution analogous to the one proposed for influenza B viruses providing information that would be beneficial for future immunization programs and to design safe vaccines.

Population-based study of acute respiratory infections in children, Greenland

Acute respiratory infections (ARI) are frequent in Inuit children, in terms of incidence and severity. A cohort of 294 children <2 years of age was formed in Sisimiut, a community on the west coast of Greenland, and followed from 1996 to 1998. Data on ARI were collected during weekly visits at home and child-care centers; visits to the community health center were also recorded. The cohort had respiratory symptoms on 41.6% and fever on 4.9% of surveyed days. The incidence of upper and lower respiratory tract infections was 1.6 episodes and 0.9 episodes per 100 days at risk, respectively. Up to 65% of the episodes of ARI caused activity restriction; 40% led to contact with the health center. Compared with studies from other parts of the world, the incidence of ARI appears to be high in Inuit children.

Implications of health care provision on acute lower respiratory infection mortality in Bangladeshi children

This study uses a geographic information system to evaluate the effects of health care provision on acute lower respiratory infection (ALRI) mortality in very young children in rural Bangladesh. Since 1988, an ALRI control program has been operating in a rural area of Bangladesh in an effort to decrease morbidity and mortality of children suffering from ALRI. ALRI-specific mortality data for very young children (<2 years of age) were obtained from a surveillance system of the area from 1988 to 1993. The ALRI mortality data were aggregated by clusters of households called baris. In order to avoid bias in the population size of haris, spatial moving averages of ALRI-specific death rates were calculated. The relationships between ALRI death rates and several environmental and health service provision variables were measured using regression analysis. The results show that the ALRI mortality rate was 54% lower in the community-based ALRI control program area than in a comparison area where there was no intervention. Greater access to allopathic practitioners was related to lower ALRI mortality rates while access to indigenous practitioners was related to higher mortality. In conclusion, the benefit of the community-based ALRI control program, using a simple case management strategy and improved access to allopathic practitioners, should be replicated in other rural areas of Bangladesh in an effort to reduce child ALRI mortality.

Risk factors for mortality among children hospitalized because of acute respiratory infections in Bangui, Central African Republic

BACKGROUND

Acute respiratory infections are the most common cause of death in children in developing countries. Little information is available on risk factors for mortality among African children presenting with symptoms compatible with acute respiratory infections.

OBJECTIVE

To identify risk factors for death among children hospitalized for respiratory complaints who satisfy the WHO clinical definition for pneumonia or severe pneumonia.

METHODS

Children <5 years of age who presented with cough and/or difficult breathing and were hospitalized in Bangui during a 1-year period were investigated for risk factors for mortality. The study population consisted of 395 children who satisfied the WHO clinical definition for pneumonia/severe pneumonia. The associations between death and demographic, nutritional, socioeconomic, laboratory and clinical variables were examined.

RESULTS

Of the 49 (12.4%) children who died, all but one had had indrawing of the chest which, in univariate analysis, was the risk factor most strongly associated with death [odds ratio, 22.99; 95% confidence interval (CI), 3.81 to 935.2]. In a multivariate model the independent risk factors for death were indrawing of the chest [adjusted odds ratio (AOR) 8.35, CI 1.04 to 66.82], hepatomegaly (AOR 6.72, CI 2.35 to 19.21), age between 2 and 11 months (AOR 6.37, CI 2.18 to 18.59), grunting (AOR 4.53, CI 1.96 to 10.45), a moderate/severe alteration of general status (AOR 3.23, CI 1.17 to 8.94) and acute malnutrition (AOR 2.74, CI 0.96 to 7.78).

CONCLUSIONS

These findings could be used in flow charts for the management of children with respiratory complaints to identify children at increased risk of death who need to receive aggressive therapy.

Early predictors of mortality in pneumococcal bacteraemia

OBJECTIVES

Pneumococcal bacteraemia carries a mortality of about 20%. Approximately 50% of deaths from pneumococcal bacteraemia occur within the first 48 h of admission. In order to influence outcome, critically ill patients should be identified at the time of presentation. This study enables the clinician to rapidly make an evidence-based assessment of a patient's prognosis, allowing the identification of patients who should be placed in a high-risk category at an early stage, when appropriate management is most likely to be effective.

METHODS

Data were collected from the medical record of history, physical examination, radiological examination and laboratory investigations done on initial presentation using a standardized proforma. The data were first examined by Pearson's Chi-squared test, with Yates' correction if needed. Variables found to be significantly associated with case fatality ( P < 0.05) by these methods were examined by stepwise logistic regression analysis in order to identify those factors which were independent predictors of case fatality.

RESULTS

The overall case fatality was 21%. Older age, apyrexia, tachypnoea, bilateral consolidation, hypoalbuminaemia, elevated aminotransferases, renal impairment, acidosis and leucopaenia were significantly associated with higher case fatality. Older age, acidosis and elevated serum alanine aminotransferase (ALT) were independent predictors of case fatality. Fifty-five percent of isolates belonged to serotypes 4, 6B, 9V, 14, 19F and 23F, to which good antibody levels have been documented in both young and elderly patients post-vaccination. Serotype 14 was most common, and was significantly associated with higher case fatality. Colder weather was associated with a higher incidence of both infection and case fatality. The case fatality amongst patients receiving ITU management was 44%. Less than 50% of patients who died received ITU management.

CONCLUSIONS

Despite the increased availability of new antibiotics and vaccines, the mortality of patients with pneumococcal bacteraemia remains unchanged. The parameters above allow early identification of patients with a higher case fatality; these patients may benefit from being placed in a "high-risk" category early on in their management. Vaccination of the elderly may reduce the incidence and/or mortality from pneumococcal bacteraemia. Further studies are required to understand the reasons for referral for intensive therapy in acute pneumococcal bacteraemia and whether ITU management affects outcome.

Capsular type distribution and susceptibility to antibiotics of Streptococcus pneumoniae clinical strains isolated from Uruguayan children with systemic infections. Pneumococcus Study Group

Children under 24 months of age are at high risk for serious infection with Streptococcus pneumoniae but they do not elicit effective immune responses to the currently available capsular polysaccharide vaccines. A polysaccharide protein conjugated vaccine involving the most frequent types has become an urgent need. To produce such a vaccine for Latin America, information on type distribution is required. Recently, Uruguay was 1 of the 6 countries in Latin America where surveillance for invasive pneumococcal infections in children under the age of 5 years was carried out. Seventy percent of the 182 invasive S. pneumoniae isolates were recovered from patients under 24 months of age, and 19% were recovered from infants under 6 months. The 7 most frequent types were 14, 5, 1, 6B, 3, 7F, and 19A; representing 80% of invasive isolates. Twenty-one types were identified, 16 in pneumonia and 14 in meningitis. Resistance to penicillin increased during the study period, from 29% in 1994, to 40% in 1995-1996, mainly because of the spread of type 14 strains resistant to penicillin and trimethoprim/sulphamethoxazol (89% of resistant isolates). The high proportion of systemic pneumococcal infections recorded in patients under 24 months of age and the increasing resistance of these agents to first-choice antibiotics point to an urgent need for a capsular polysaccharide protein conjugated vaccine.

The day care center as a risk factor for acute respiratory infections

BACKGROUND

This study was conducted to assess the magnitude of the risk of high morbidity (> or = 7 episodes/year) for acute respiratory infections (ARI) in infants attending day care centers (DCC), and to compare the incidence, duration, and severity of ARI in children staying at home (Home).

METHODS

Using a cohort design, 282 infants (DCC, 138 and Home, 144) were followed for a year. Age at entry into the study ranged from 43 days to 4 months. During follow-up, social workers interviewed the mothers weekly to register whether the infants had an ARI. Also, infant health conditions and physical growth were updated monthly.

RESULTS

ARI incidence was 14 episodes per child/year among DCC infants with a median of 74 sick days, while among children at home, the ARI incidence was 6 episodes, and the median was 40 days. The incidence density ratio for DCC children was 2.33 (95% CI, 2.13-2.54); after adjusting for other covariates, the relative risk increased to 5.27 (95% CI, 3.54-7.83).

CONCLUSIONS

Infants attending DCCs will suffer ARI more frequently than children cared for at home. We did not find seasonal variations in the incidence rates among DCC infants. The quality of care provided at these facilities should be analyzed in more depth for proposing measures to decrease ARI incidence.

The rationale for population-based surveillance for Haemophilus influenzae type b meningitis

Although Haemophilus influenzae type b (Hib) conjugate vaccines have been spectacularly successful, nearly eradicating Hib disease in countries where used routinely, they are relatively expensive. In many countries the incidence of Haemophilus influenzae type b (Hib) disease is uncertain, and it is unclear whether the local burden of Hib disease warrants the costs of adding Hib vaccine to the routine immunization program. Population-based surveillance to assess the local burden of Hib disease can help decision makers with this process. Although pneumonia is more common than meningitis, surveillance for Hib meningitis and invasive disease is likely to be more feasible and efficient than surveillance for Hib pneumonia. Standardization of laboratory methods for the isolation and identification of H. influenzae from CSF specimens is essential to successful surveillance. Should a country decide to introduce Hib conjugate vaccine as a routine immunization, population-based surveillance data collected before and after the introduction of vaccine can be used to monitor its impact. Finally population-based surveillance for bacterial meningitis also can provide information on the incidence of pneumococcal and meningococcal infections and on serogroup or serotype distributions that will be important when evaluating the new vaccines for those pathogens that are being developed.

Case-control study of the role of nutritional rickets in the risk of developing pneumonia in Ethiopian children

BACKGROUND

Pneumonia is the most important cause of morbidity and mortality in children aged under 5 years worldwide. Studies in developing countries have suggested an association between nutritional rickets and pneumonia. Since both nutritional rickets and pneumonia are common in Ethiopia, we did a case-control study to determine the role of nutritional rickets in the development of pneumonia.

METHODS

Cases were children younger than 5 years admitted to the Ethio-Swedish Children's Hospital during a 5-year period with a diagnosis of pneumonia (n = 521), but data were incomplete for 21 of these and they were not included. Controls (n = 500) were matched for admission within 3 months of cases and age within 3 months and had no evidence of pneumonia. Nutritional, demographic, and clinical and radiographic data for rickets and pneumonia were collected. Matched odd ratios and logistic regression were used to test the significance of the association of rickets and pneumonia.

FINDINGS

Rickets was present in 210 of 500 cases compared with 20 of 500 controls (odds ratio 22.11). There were significant differences between cases and controls for family size, birth order, crowding, and months of exclusive breastfeeding (p < 0.05). After correction for these confounding factors by logistic regression, there was still a 13-fold higher incidence of rickets among children with pneumonia than among controls (13.37 [95% CI 8.08-24.22], p < 0.001).

INTERPRETATION

Vitamin D or calcium deficiency may be important predisposing factors for pneumonia in children aged under 5 years in developing countries. Efforts to prevent vitamin D deficiency or calcium supplementation may result in significant reductions in morbidity and mortality from pneumonia in these children.

Attendance at day care centers increases the risk of childhood pneumonia among the urban poor in Fortaleza, Brazil

We carried out a case-control study to investigate risk factors for childhood pneumonia in two groups of 650 children aged under two years in the city of Fortaleza, Ceará, Brazil. The cases were children recruited at the main pediatric hospital with a radiological diagnosis of pneumonia, and controls were children of the same age group recruited from the neighbourhood of the cases. In this paper we focus on variables related to childcare practices. Working mothers, proportion of time the mother had worked since the child was born, and use of day care centers emerged as important risk factors with estimated relative risks of 1.58, 1.76 and 5.22, respectively. Also important were the number of children living in the house and presence of grandparents. However, the presence of siblings under two years and the birth order were not associated with pneumonia. All analysis included adjustment for confounding by income, parents' education, and other risk factors as appropriate. This is the first study from a developing country to identify attendance at day care centers as a risk factor for increased childhood morbidity, in this case pneumonia. This finding is of significant public health importance for countries such as Brazil with growing urban populations and an increasing need by mothers to find work outside the home.

A one-year community study of under-fives in rural Ethiopia: patterns of morbidity and public health risk factors

A prospective weekly home surveillance study was undertaken to determine morbidity patterns within the Butajira Rural Health project in central Ethiopia. Overall prevalence of illness was 5.8% in 1216 person-years observed among rural Ethiopian children aged under 5 years. Acute respiratory infections (ARI) (prevalence 2.8%) and acute diarrhoea (2.4%) were the commonest conditions. Episodes of illness were distributed unequally among children, with a mean of 2.34 episodes per child. These included an average of 1.13 episodes of ARI (of which 0.16 had lower respiratory symptoms [ALRI]) and 1.17 episodes of acute diarrhoea. Sanitation factors were the principal risks for gastroenteritis, while living in rural areas predisposed children to ARI. Parental factors such as illiteracy were also linked to morbidity.

Etiology and severity of community acquired pneumonia in children from Uruguay: a 4-year study

The 4-year study (1987-1990) covered the major clinical-epidemiological characteristics of pneumonia in children as diagnosed at the emergency service of the Children's Hospital, as well as etiologies, and factors involved in the most severe cases. Etiology was determined in 47.7% of the 541 pneumonia cases, involving 283 pathogens of which 38.6% were viruses and 12.6% bacteria. Viral and mixed etiologies were more frequent in children under 12 months of age. Bacteria predominated in ages between 6 and 23 months. Among the viruses, respiratory syncytial virus predominated (66%). The bacterial pneumonias accounted for 12.2% of the recognized etiologies. The most important bacterial agents were S. pneumoniae (64%) and H. influenzae (19%). H. influenzae and mixed infections had a relevant participation during the 1988 season, pointing to annual variations in the relative participation of pathogens and its possible implication in severity of diseases. Correlation of severity and increased percentage of etiological diagnosis was assessed: patients with respiratory rates over 70 rpm, or pleural effusion and/or extensive pulmonary parenchyma compromise yielded higher positive laboratory results. Various individual and family risk factors were recognized when comparing pneumonia children with healthy controls.

Acute respiratory infections in children from a deprived urban population from Uruguay

To obtain base line data on incidence, duration, clinical characteristics and etiology of acute respiratory infections (ARI), 276 children from deprived families living in Montevideo were followed during 32 months. The target population was divided into two groups for the analysis of the results: children aged less than 12 months and those older than this age. During the follow-up period 1.056 ARI episodes were recorded. ARI incidence was 5.2 per child/year. It was 87% higher in infants than in the older group, as was the duration of the episodes. Most of the diseases were mild. Tachypnea and retractions were seldom observed, but 12 children were referred to the hospital, and 2 infants died. Viral etiology was identified in 15.3% of the episodes. RSV was the predominant agent producing annual outbreaks. Moderate to heavy colonization of the upper respiratory tract by Streptococcus pneumoniae (32.3%) and Hemophilus sp. (18.9%) was recorded during ARI episodes. This community-based study furnish original data on ARI in Uruguay. It enabled to assess the impact of these infections on childhood.

Difficulties encountered in a community-based study of acute respiratory infections in Uruguay

A cohort study on acute respiratory infections, involving 270 children observed by pediatricians in their homes every 10 days over a period of 32 months, gave the opportunity to experience logistic and methodological problems seldom described in the literature. The purpose of this article is to alert researchers as to the difficulties faced when performing community-based studies in developing countries. Although a carefully planned project was undertaken, problem areas included the establishment of the target population, population dynamics, field related problems, laboratory aspects and data management. It is hoped that other investigators may benefit from the extensive experience gained from our program in foreseeing and coping with the difficulties involved.